.password-btn {
    position: relative;
    width: 345px;
    height: 40px;
    background-color: goldenrod;
}

.password-btn > input {
    padding-left: 42px;
    padding-right: 10px;
    border: 2px solid lightgray;
    width: 100%;
    height: 100%;
}

.password-btn > span {
    position: absolute;
    left: 5px;
}

 /*:before元素会将content的内容写到span的前面*/
.password-btn > span:before {
    content: "\263a";
    font-size: 30px;
}